Laws are fleeting, age limits go up and down, but what really makes you a man (adult) is merely ownership of your actions and being responsible. Warren is dead on. I've raised a stepson and two daughters, and you can't be independent (making all of your own decisions) and still have your parents paying for your life. If they are ok with your smoking, then fine. But, when you step up and do the right thing by telling them, and they don't like it, your only two correct responses are to quit or start paying your own way. It's as simple as that. Just tell them as if you're talking about what you did that day. It's just a thing, right?
But skulking around behind their back, while they pay for your electricity, roof, cable, food, etc...is not setting off on a "manly" path. It's more what a child would do. You cannot rely on laws to hide behind and say you're a man. You have to walk the walk.